Hemodynamic and metabolic effects of prostacyclin after coronary bypass surgery

The hemodynamic and metabolic effects of prostacyclin (PGI2) were assessed in 12 patients who underwent coronary bypass surgery. PGI2 were injected intravenously at a rate of 2.5 ng/kg/min for 10 minutes, followed by three consecutive 10-minute injections of 5, 10 and 20 ng/kg/min. PGI2 infusion decreased systolic and diastolic arterial pressures by 17% (p less than 0.001) and increased cardiac index by 17% (p less than 0.001) without changing the heart rate. Right atrial, pulmonary arterial and pulmonary wedge pressures remained essentially unchanged. Total vascular resistance decreased by 37% (p less than 0.001). Rate-pressure product, an index of myocardial oxygen consumption, decreased by 13% (p less than 0.01), while stroke work index did not change. A 36% decrease in arterial PO2 (p less than 0.001) was the most consistent metabolic effect induced by PGI2 infusion. However, oxygen transport increased by 11% (p less than 0.05), suggesting that no decrease in peripheral oxygen supply was produced. Thus, PGI2 improved cardiac function and performance by a predominant effect on total vascular resistance. It may be valuable in the management of patients who undergo coronary artery surgery.